1. Field of the Invention
This invention generally relates to an X-ray diagnostic apparatus in which a transmitted X-ray image of an object under examination, e.g., a patient, is available for diagnostic purposes, and more particularly, to an X-ray diagnostic apparatus by which visible X-ray images of the object can be obtained, based only upon primary X-rays, without any adverse influences caused by the scattered X-rays.
2. Description of Prior Art
Generally, in the X-ray diagnostic apparatus set forth in the preamble, X-rays incident on an X-ray detector through the object such as a patient contain not only primary X-rays but also X-rays which are scattered by the object under examination. The scattered X-rays constitute one of the major causes of deteriorated contrast and resolution in the transmitted X-ray image. This makes it necessary to eliminate an image component on the scattered X-rays from the transmitted X-ray image data as sensed and provided by the detector.
One of the approaches to eliminate the scattered X-ray component is to use a so-called "Buckey Blade" or an elimination grid for the scattered X-rays (referred to as a "grid"). This approach introduces a new problem in that there is a limit in the scattered X-ray elimination, because the grid itself may cause scattered X-rays therefrom.
The elimination of the scattered X-rays is very significant in the field of X-ray diagnosis for the reasons that it improves an image quality, such as contrast and resolution, and thus allows a logarithm conversion of primary X-rays image data, thereby obtaining an accurate attenuation quantity of X-rays caused when the X-rays pass through the object. Many studies have been made on the scattered X-rays, aiming at their effective elimination. The complicated phenomena of the scattered X-rays impede or almost reject a theoretical approach to this theme. This is the present stage of technology in this field.